I downloaded the Square app from the Android market (free). The cool thing about this app is it allows you to process credit card transactions on your Android phone (iPhone and iPad versions available too). The even cooler part... when you login to the squareup.com site on a PC and fill out all the information, they send a free "square" that plugs into the phone's headphone jack and reads the magnetic strip on a swiped credit card!
The square app has email receipts with the transaction location and map on the receipt along with an optional picture of your choosing. Rates are on a per transaction basis and reasonable especially since there are no fees for hardware, software, separate merchant account, etc.
My "square" is on the way and will hopefully be here in a few days. I'll post an update when I've tried it out.
UPDATE: The Square came in the mail in just a few days. It fits very nicely in the headphone jack and works great. I also associated my checking account online. They made two small deposits and one withdrawal (the sum of the two deposits). I entered those in my account setup to validate the associated checking account and now I'm free to process credit cards and receive the money in my bank account. I can see this coming in handy for people in service industries (e.g. onsite computer support, wrecker drivers, etc.) or, more likely for me, at a yard sale when the interested buyer just doesn't have enough cash to buy that old couch. Great idea by the Square Inc. guys and I hope to you use it more soon.